High performance readout electronics for uncooled infrared detector arrays

Yıldırım, Ömer Özgür
This thesis reports the development of high performance readout electronics for resistive microbolometer detector arrays that are used for uncooled infrared imaging. Three different readout chips are designed and fabricated by using a standard 0.6 m CMOS process. Fabricated chips include a conventional capacitive transimpedance amplifier (CTIA) type readout circuit, a novel readout circuit with dynamic resistance nonuniformity compensation capability, and a new improved version of the CTIA circuit. The fabricated CTIA type readout circuit uses two digital-to-analog converters (DACs) with multiple analog buses which compensate the resistance nonuniformity by adjusting the bias currents of detector and reference resistors. Compensated detector current is integrated by a switched capacitor integrator with offset cancellation capability followed by a sample-and-hold circuit. The measured detector referred current noise is 47.2 pA in an electrical bandwidth of 2.6 KHz, corresponding to an expected SNR of 530. The dynamic nonuniformity compensation circuit uses a feedback structure that dynamically changes the bias currents of the reference and detector resistors. A special feature of the circuit is that it provides continuous compensation for the detector and reference resistances due to temperature changes over time. Test results of the fabricated circuit show that the circuit reduces the offset current due to resistance nonuniformity 42.5 times. However, the calculated detector referred current noise is 360 pA, which limits the circuit SNR to 70. The improved CTIA type readout circuit introduces a new detector biasing method by using an additional auxiliary biasing transistor for better current controllability. The improved readout circuit alleviates the need for high resolution compensation DACs, which drastically decreases the circuit area. The circuit occupies an area of one seventh of the first design. According to test results, the current compensation ratio is 170, and the detector referred current noise is 48.6 pA in a 2.6 KHz bandwidth.


Development of electrochemical etch-stop techniques for integrated MEMS sensors
Yaşınok, Gözde Ceren; Akın, Tayfun; Department of Electrical and Electronics Engineering (2006)
This thesis presents the development of electrochemical etch-stop techniques (ECES) to achieve high precision 3-dimensional integrated MEMS sensors with wet anisotropic etching by applying proper voltages to various regions in silicon. The anisotropic etchant is selected as tetra methyl ammonium hydroxide, TMAH, considering its high silicon etch rate, selectivity towards SiO2, and CMOS compatibility, especially during front-side etching of the chip/wafer. A number of parameters affecting the etching are inv...
Reliability improvement of RF MEMS devices based on lifetime measurements
Gürbüz, Ozan Doğan; Demir, Şimşek; Akın, Tayfun; Department of Electrical and Electronics Engineering (2010)
This thesis presents fabrication of shunt, capacitive contact type RF MEMS switches which are designed according to given mm-wave performance specifications. The designed switches are modified for investigation in terms of reliability and lifetime. To observe the real-time performance of switches a time domain measurement setup is established and a CV (capacitance vs. voltage) curve measurement system is also included to measure CV curves, pull-in and hold-down voltages and the shifts of these due to actuat...
A low-cost uncooled infrared detector array and its camera electronics
Akçören, Dinçay; Akın, Tayfun; Eminoğlu, Selim; Department of Electrical and Electronics Engineering (2011)
This thesis presents the development of integrated readout electronics for diode type microbolometers and development of external camera electronics for microbolometers. The developed readout electronics are fabricated with its integrated 160x120 resolution FPA (Focal Plane Array) in the XFAB SOI-CMOS 1.0 μm process. The pixels in the FPA have 70 μm pixel pitch, and they are sensitive in the 8–12 μm band of the infrared spectrum. Each pixel has 4 serially connected diodes, and diode turn on voltage changes ...
High performance CMOS capacitive interface circuits for MEMS gyroscopes
Silay, Kanber Mithat; Akar, Tayfun; Department of Electrical and Electronics Engineering (2006)
This thesis reports the development and analysis of high performance CMOS readout electronics for increasing the performance of MEMS gyroscopes developed at Middle East Technical University (METU). These readout electronics are based on unity gain buffers implemented with source followers. High impedance node biasing problem present in capacitive interfaces is solved with the implementation of a transistor operating in the subthreshold region. A generalized fully differential gyroscope model with force feed...
Analysis and design of passive microwave and optical devices using the multimode interference technique
Sunay, Ahmet Sertaç; Birand, Mehmet Tuncay; Department of Electrical and Electronics Engineering (2005)
The Multimode Interference (MMI) mechanism is a powerful toool used in the analysis and design of a certain class of optical, microwave and millimeter wave devices. The principles of the MMI method and the self-imaging principle is described. Using this method, NXM MMI couplers, MMI splitter/combiners are analyzed. Computer simulations for illustrating the "Multimode Interference Mechanism" are carried out. The MMI approach is used to analyze overmoded 'rectangular metallic' and 'dielectric slab' type of wa...
Citation Formats
Ö. Ö. Yıldırım, “High performance readout electronics for uncooled infrared detector arrays,” M.S. - Master of Science, Middle East Technical University, 2006.